Collapsible boring head



1957 I E. ANDERSON 2,808,250

COLLAPSIBLE BORING HEAD Filed July 17,1956 3 Sheets-Sheet 1 /4- I 17 /0 //L /I a /7 Flg. 1 15 i I 2/ /a INVENTORQ Edward L. Anderson BY T RNEV Oct. 1, 1957 E. ANDERSON 2,808,250

COLLAPSIBLE BORING HEAD Filed July 1'7, 1956 3 Sheets-Sheet 2 8/ 7 eg a9 39 I0 49 Q 38 42 47 s k 43 Q 48 27 44 I06 a 26 53 24 mmn 4 4 {0 23 22 3/ X a 73 g l 43 I 46 Q 47 g IN V EN TOR.

BY Edward. L. Anderson ATTORNEY Oct. 1, 1957 E. L. ANDERSON 2,808,250

COLLAPSIBLE BORING HEAD Filed July 1'7, 1956 5 Sheets-Sheet 3 IN V EN TOR.

Edward L. Anderson i a. QLQM ATTORNEY United States Patent M COLLAPSIBLE BORING HEAD Edward L. Anderson, Chicago, 111., assignor to Good an lfigiillllfadlll'l ilg Company, Chicago, 111., a corporation of mors Application July 17, 1956, Serial No. 598,359

4 Claims. (Cl. ZGZ I) This invention relates to improvements in boring heads for mining machines of the type in which at least one boring head is rotatable on a horizontal axis in advance of the machine, each boring head consisting of a rotatable hub having a plurality of radially extending arms on which are mounted forwardly projecting cutter supports. Boring heads of this general character usually include means for collapsing or retracting the outer ends of the arms to facilitate Withdrawal of the head from the bore, and also for clearance while transporting or tramming the mining machine from place to place in the mine.

More particularly, the present invention relates to an improvement in the type of telescopic adjustment for the outer ends of the arms such as shown in Anderson et al. Patent No. 2,772,870, on a rotary boring head whereby the adjustment may also permit the boring head to cut bores of different diameters. The present invention makes use of a worm and gear arrangement providing economy of space such that a greater range of radial extension or retraction can be had in a given size of boring head.

The principal object of the present invention is to provide a simple and eflicient boring head structure, having telescopic end portions at the outer ends of the arms.

Another object of the invention is to provide a simple form and arrangement of means for simultaneously adjusting the telescopic end portions of a plurality of the arms relative to the hub.

The invention may best be understood by reference to the accompanying drawings, in which- Figure l is a front view of a boring head constructed in accordance with the invention;

Figure 2 is a vertical section of the boring head shown in Figure 1;

Figure 3 is a section taken on line 3 3 of Figure 2; and

Figure 4 is a section view taken on line 44 of Figure 3.

Referring now to details of the embodiment of the invention shown in the drawings, indicates a boring head driven by a shaft 11 through splines 12. Mounted on the front of the boring head 10 is a center drill 13 having drill bit 14 socketed in its forward extremity. The hub 10a of boring head 10 has a relatively short cutter arm 15 with a cutter support 16 having cutters 17 socketed in its forward and outward extremity.

The hub also has a pair of aligned hollow inner arm members 10b extending radially therefrom, in which radially extensible arms 18 are telescopically mounted. The extensible arms 18 have cutter supports 19 projecting forwardly from their outer ends, with .cutters 17a mounted at their forward extremities. Said arms may also have sweeps 21 on the appropriate sides for removing cuttings, as usual. The ends of the inner arm members 10a are sealed against the telescopic arms 18 by wiper gaskets 79 and backing plates 81.

The hub 10a is secured against axial movement rela- .tive to shaft 11 by a plug 22 fastened to the end of shaft 2,808,250 Ratente Oct. 1, 19 7 11 by screws 23. The aligned inner arms 10b have a through bore 24 with key slots 26 and 27 along the inner arms. The hub 10a has axially stepped bores 28, 29 and 31 adjacent the front end of shaft 11 which increase in diameter toward the front of said hub. The front face of the'hub has stepped axial bores 32 and 33 of still larger diameter than the bores 28, 29 and 31. An axially offset bore 34 is formed parallel to and between the stepped bores 28 and 32 to accommodate a part of the gearing. An access hole 36 with a cover plate 37 is provided at one side of the hub, the purpose of which will be described later.

Each of the radially extensible arms 18 has a pair of key seats 38 having keys 39 fitting therein cooperating with the key slots 26 and 27 along the inner arms 10b. Each e s b m also has areal stepped bores 41, 42, 43 and 44 of increasing diameter toward its inner end. A righthand, interiorlythreaded nut 46 is fitted into the bore 42 of one arm and locked against rotation by a pin 47 secured beneath key 39. The nut is secured against axial movement by locking ring 48. A similar lefthand, interiorly threaded nut 49 is fitted in bore 42 of the opposite radial arm 18 and secured in like manner as nut 46.

A worm shaft 51 has a screw shaft 52 fixed at one end having righthand threads for engagement with nut 46, and an opposed screw shaft 53 having lefthand threads for engagement with nut 49, so that rotation of the worm shaft in one direction will draw the extensible arms 18 toward each other and rotation in the opposite direction will thrust said arms apart. In the form shown, the worm shaft 51 is integral with the screw shafts 52 and 53 and also has an integral thrust shoulder 54 at the inner end of screw shaft 52, and a detachable thrust collar 56 fastened by screws 57 to the inner end of screw shaft 53. The shoulder 54 and collar 56 hold the worm shaft 51 centered in a housing 58 having a stepped annular base 58a fitting in bores 32 and 33 and secured to the hub 10a by screws 59.

Referring now more particularly to Figures 3 and 4, a worm gear 61 is keyed at 62 on worm shaft 51 within the housing 58. The housing has bearings 63 for the Worm shaft 51 and thrust Washers 64 are associated therewith. A worm 66 coa-cts with the teeth of worm gear 61. Said worm has shaft portions 66a and 66b journalled in bearings 67 and 68. Bearing 67 is in the base 58a of housing 58. Bearing 68 is demountably secured to the housing 58 by key 69 and screws 71 for purposes of assembly. The inner shaft extension 6611 of worm 66 has a spur pinion 72 keyed thereon at 76. Pinion 72 meshes with a spur gear 73 fixed on a control shaft 74 by key 77 and nut 78. The control shaft extends through the hollow drive shaft 11 and is rotated by suitable control means (not shown) at the opposite end of said drive shaft.

In operation the shaft 74 may be rotated either forwardly or reversely by any suitable means to cause the arms 18 to extend or retract vertically. This arrangement of parts allows the bore diameter formed between the cutter supports 19 at the ends of the telescopic arms 18 to be varied in any increment within the retraction range, which is considerably increased because of the novel design of the worm and worm gear drive for the screw shafts 52 and 53, and the arrangement whereby the shoulder 54 and collar 56 on said shafts can be telescoped in the recessed bore 44 in the arms 18.

The parts can be readily assembled or disassembled, making use of the detachable housing 58 at the front of the hub and the access hole 36 at one side of said hub.

Although I have shown and described a preferred embodiment of my invention, it is to be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifica 1. In a rotary boring head comprising a hollow huh and two aligned radial arms, each of said arms comprising a hollow inner arm section and a cutter carrying telescopic outer end section, each of said inner arm sections having a bore opening to its outer end in which one of said telescopic end sections is keyed for slidable movement, said hollow hub having a concentric bore in its front face, a supporting member detachably mounted in said front bore and extending inwardly therefrom, a screw having a bearing portion journalled in said supporting member and left and righthand threaded end portions extending along said hollow inner arm sections for threaded engagement with the inner ends of said telescopic end sections, a worm gear fixed on said screw shaft, a worm engageable with said worm gear and rotatable on said supporting member on an axis offset laterally from the axis of rotation of said hub, and means in said hub for rotating said worm to effect adjustment of said telescopic end sections relative to said inner arm sections including a control shaft disposed concentrically of the hub and having a pinion engaged with a spur gear fixed on said worm.

2. The structure of claim 1, wherein each of the telescopic end sections has a nut detachably mounted in its inner end for threaded engagement with the adjacent end of the screw shaft.

3. The structure of claim 1, wherein the supporting member consists of a housing, the worm on the screw shaft is disposed in said housing, the screw shaft has thrust collars engaged with the opposite outer faces of said housing, at least one of which thrust collars is detachably mounted on said screw shaft, and said hub has an auxiliary side opening alTording access to said detachable thrust collar.

4. The structure of claim 3, wherein the housing has a bearing for the inner end of the worm' detachably mounted on the inner end of said housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,698,862 Wadell Jan. 15, 1929 1,953,402 Graham Apr. 3, 1934 2,011,940 Myers Aug. 20, 1935 2,043,679 Tarasuk June 9, 1936 

